I'll add one more suggestion, just for fun: (it's Cheesenugget's fault, she started it with adding a Gray banded king...)
I'm very partial to Trans Pecos rat snakes (Bogertophis subocularis...also called a "suboc" for short), & if you can get your hands on the Dusty Rhodes book "The Complete Suboc" it would be worth a look. My adults are about 4'- comparable to an adult corn snake- & they also do great (as adults) in a 40 gal. breeder tank (3' long x 18"). These are very gentle snakes with big eyes- they're nocturnal, but good sports even by day, easy to feed f/t mice, & very calm to handle- they tend to move slow, though they can move quite fast when they want to (as in catching prey)! They're not as common as corn snakes, but they're available captive-bred. It might be a good fit for you also? I've bred them in the past, & currently have 3. They like & will use branches, & do fine with room temperatures (my house is 70* winter & up to 80* summer) using just UTH @ one end of tank, and they also appreciate a black or red incandescent bulb at night in winter- they'll often snooze in their branches (they also have attached baskets, lol) under the "light" that is dimmed way down. They also use warm & cool hides. These are desert snakes, so screen tops with good air-flow is a must. (Don't add any humidity.)